This invention relates to a control valve assembly for use in pneumatic paving breakers and other similar pneumatic reciprocating motors.
Paving breakers are well known and generally comprise a free piston which is reciprocable within a cylinder powered by compressed air and which at the bottom of its stroke strikes a tappet or anvil located directly above a tool, the latter resting on the surface being worked. The reciprocating motion of the piston is achieved by feeding compressed air alternately to each end of the piston under the control of a control valve assembly. A port is also provided in the cylinder to enable exhaust of air from each end of the piston, alternately, as it reciprocates in the cylinder. Moreover, as the energy to be imparted to the piston on its return stroke is substantially less than that for the working stroke it is essential to meter the flow of air to the underside of the piston so that there is a minimum consumption of air supplied for the return stroke. Furthermore, the speed of response of the valve is critical if efficient use is to be made of the compressed air available.